Intermittent absorption refrigerating apparatus and method



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INTEHMITTENT ABSORPTION REFRIGBRATING APPARATUS AND METHOD Filed March 18, 1951 IN VENTOR. D. 514mm.

Patented May it, 1935 INTERMIITTENT i illiN REGIE t1:

ATING APPARATUS RETHOD Donald E. Knight, Brooklyn, NY assignor to Electrolux Servel Corporation, New Yorh, N. lifi, a corporation of Delaware Application March 1d, 1931, S eri No. 523,394

30 mailman.

This invention relates to refrigeration, and more particularly to refrigeration apparatus of the intermittent absorption type.

In refrigeration apparatus of this type, a re- 5 frigerant fiuid is expelled from an absorbent by heat during a period variously referred to as a heating or generating period. During this period, the expelled refrigerant vapor is' condensed to liquid and the liquid refrigerant accumulated in an evaporator or reservoir. After distillation of the desired amount of refrigerant, the heating is discontinued and the absorbent cooled, whereby the pressure in the system is lowered to initiate what is variously referred to as a refrigeration or absorption period. During this period, liquid refrigerant evaporates in the reservoir or evaporator and is absorbed into the absorbent from which it was previously distilled. A suitable cooling medium, such as water or air, is utilized to remove the heat of condensation during the generating period, and to remove the heat of absorption during the refrigeration period. Since the absorbent is alternately heated and cooled, it has been necessary to provide, in addition to a control for the heating means, an additional means for control of the cooling medium, and these controls must be carefully synchronized to avoid excessive heat losses.

In accordance with my invention there is provided a refrigeration apparatus of this type operating with continuous cooling during both the generating and refrigerating periods.

A further object ofthe invention is to provide such an apparatus having a single element for dissipating both heat of condensation and heat oi absorption to the cooling medium.

It is also an object oi? the invention to provide such an apparatus in which the changes between the alternate periods of the cycle are effected solely by control of the heat input.

These objects are attained, in general, by providing a new and novel secondary heat transfer system which is operative responsive to the intermittent heating of the absorbent to transfer heat alternately from the generator-absorber and condenser of an intermittent refrigeration apparatus to the cooling medium.

A fuller understanding of my invention may be had and the objects and advantages thereof will be apparent from the following description taken in connection with the accompanying drawing in which the figure shows schematically a refrigerating apparatus of the intermittent absorption type contemplated by this invention.

In the figure, the generator comprises a hollow (til. 62-5) wall formed by an outer shell ill and a concentric inner shell ii spaced apart and enclosing an annular chamber l2. Within the generator is disposed a vessel it spaced from the shell i l and open at the bottom to the interior of the generator. Within the vessel i3 and adjacent the bottom thereof is a heating means 9 which may be of any suitable type such as a flue or electric heating element. The top of vessel i3 is connected through a rectifier, shown as a coil it, to the condenser it. The latter consists of a plurality of small vertical pipes it connected to a header at each end and surrounded by an outer casing enclosing a fluid tight chamber i'l through which the tubes extend. The rectifier it is connected to the lowerheader oi the condenser and the upper header is connected through pipe it to the evaporator it. The latter consists of an outer casing it within which is disposed a concentric vessel 2 ll open at the top and forming an annular space it with the outer casing it. The lower part of the vessel 2i is connected to the upper part of the annular space by a pipe it locatedoutside oi the evaporator. The lower portion of the vessel ii may be extended through the casing it, as illustrated, to provide a connection for the pipe 2t.

Before heat is supplied, the solution of refrigerant in absorption liquid is at the same level within the vessel it as in the generator. During the heating or generating cycle refrigerant gas generated outside of the vessel it cannot escape and accumulates in the upper part of the generator under the top of the inner shell ll. Due to the pressure of this accumulated gas, the liquid outside of vessel it is depressed and forced upwardly into the vessel until the gas bubbles upwardly through the opening in the bottom. In rectifier it, due to the surface exposed to air, any absorption liquid vapor is condensed from the refrigerant gas and flows back to the generator by gravity. The refrigerantgas flows upwardly from the rectifier into the condenser it where it condenses within the tubes it due to the heat transfer to the cooling medium flowing in chamber i'l around these tubes, and, due to the gas pressure from below, the condensed refrigerant is forced upwardly out of the condenser through the pipe it into the evaporator where it is forced upwardly in the clearance space it, between the inner vessel ill and the casing it, into theopening in the top of the vessel it and [collects in the latter during the generating cycle.

The above described flow of liquid refrigerant from the condenser l5 upwardly into the evaporator I9 is due to the gas pressure below the liquid which forms by condensation in the condenser. The small condenser tubes l6 are of such diameter, depending on the refrigerant utilized, that gas and liquid cannot pass each other therein, wherefore the increasing quan tity of liquid formed by condensation in the upper part of the condenser tubes cannot fiow downwardly therein, and must therefore accumulate upwardly until overflow occurs into the inner shell 2| of the evaporator l3 as previously described.

At the end of the generating cycle, when substantially all of the refrigerant has been expelled from solution in the generator, the heat input is interrupted by a thermostat responsive to generator temperature, or any other suitable means. As the temperature in the generator decreases, the pressure above the liquid refrigerant in the evaporator decreases and vaporization occurs, absorbing heat from the surrounding medium. The vapor from the evaporator passes through pipe l8, condenser 5, rectifier l4 and back to the generator, entering the top of yessel l3. In the latter, the gas pressure forces the weak absorption liquid downwardly through the opening in the bottom of the vessel l3 and into the space between the latter and the inner shell When all the liquid is forced out of the vessel l3, the gas passes through the opening in the bottom and bubbles through the absorption liquid, insuring rapid absorption. During this refrigerating cycle, the generatorabsorber is cooled by fluid in the annular space l2 as hereinafter set forth.

In the evaporator, refrigerant liquid reaches the .same level in the pipe 23 as within the ,vessel 2| and as the pressure within the apparatus decreases below that corresponding to the temperature surrounding this pipe, that is, the temperature of the medium to be cooled, boiling occurs in this pipe and, since it is of small diameter, slugs of refrigerant vapor are pumped up this pipe and into the clearance space 22 between the vessel 2| and the casing 20. In this manner, dependent upon the heat transferred to the pipe 23, liquid refrigerant is delivered by thermosyphonic action to the clearance space 22 wherein, because of its extended surface in heat exchange rela-- tion with the medium to be cooled, refrigerant liquid is delivered to the evaporating surfaces responsive to the amount of cooling required,

- that is, the difference in temperature between the medium to be cooled and the boiling point of the refrigerant. Also by this means, any absorption liquid which may have passed the rectifier during the generating cycle is returned to the generator along with the evaporated refrigerant and does not collect in the evaporator throughout successive cycles.

Cooling of this apparatus is preferably effected, as shown, by a secondary refrigerant or cooling fluid circulated through the following described secondary cooling system. The lower part of the annular space |2 in the outer wall of the generator is connected by a pipe 24 to the lower part of chamber around the condenser tubes IS. The upper part of chamber I1 is connected by a pipe 25 to a condenser 26 located above the primary condenser. The condenser 26 is cooled by water circulating through jacket 21 entering the latter through pipe 28 and discharging through pipe 29. The upper part of condenser 26 is connected by a pipe 30 to the top of a stand pipe or column 3| which extends the full height of the apparatus. The upper part of the annular space |2 in the outer wall of the generator is connected through pipe 32 to the lower part of the stand pipe 3|. Associated in heat exchange relation with the rectifier I4 is a fluid tight vessel 33 which is also connected at its lower portion with the bottom of stand pipe 3| through pipe 34. A convenient way ofassociating the rectifier l4 and the vessel 33 is to form the rectifier as a coil around the vessel as shown.

When the unit is not in operation, secondary liquid refrigerant fills the annular space |2 in the outer wall of the generator, pipes 32 and 34, and stands to the level N in pipe 24, vessel 33 and stand pipe 3|. When the cooling water is turned on in jacket 21 of the condenser 26, the temperature is reduced in this part of the system and the pressure is lowered so that the liquid in the .lower part of the system boils. The gas formed in the vessel 33 forces liquid from the latter through pipe 34 into the stand pipe 3|, raising the liquid level in the latter. Gas formed in the annular space l2 in the outer wall of the generator tends to force liquid through both pipes 32 and 24, but on account of the liquid column in the stand pipe 3|, liquid is forced through the pipe 24 into chamber ll of the condenser l5 to balance the liquid column in the stand pipe. When the unit is placed in operation, the rectifier l4 keeps the vessel 33 warm, thus preventing any liquid from returning to the vessel during the generating cycle. The heat of condensation boils the secondary refrigerant in the condenser l5 and the resulting vapor rises through pipe 25 into the condenser 26 where it is liquefied, flowing back to the primary condenser through the same pipe 25.

When the generating cycle, is completed, the input at 3 is turned oil and the generator cools by radiation and the cool vapor from the primary evaporator passing to the generator through rectifier |4 cools the latter, causing condensation of the secondary refrigerant to take place, whereupon the vessel is refilled with refrigerant liquid from the stand pipe 3| through pipe 34. As the liquid level in the stand pipe 3| decreases, the secondary refrigerant in the condenser I5 flows back through pipe 24 into the space l2 in the outer wall of the generator. Heat of absorption boils the liquid in the outer wall of the generatorabsorber and the vapors pass through the pipe 32 upwardly through the stand pipe 3| into the secondary condenser 26 where it is condensed, flowing back to the space in the outer wall of the generator through pipe 25, primary condenser l5 and pipe 24.

When the primary liquid refrigerant in the evaporator is exhausted at the end of the refrigerating cycle, no vapor passes through the rectifier |4 around the vessel 33', allowing the latter to warm up to room temperature. Also, the heat of absorption in the generator ceases, so that, relieved of this load, the secondary condenser 26 cools down to a temperature lower than that of the vessel 33, whereupon the secondary refrigerant in the latter boils, forcing liquid into the stand pipe 3| as previously described and the liquid in the outer wall of the generator is forced through pipe 24 into the primary condenser I5.

The heater 9 is now turned on and the process repeated. A more positive action may be assured by additional heating of the vessel 33 during the generating cycle as by a small gas flame which also makes it independent of room temperatures as well as adapting the system to air cooling the secondary condenser.

It will be obvious to those skilled in the art that various other changes may be made in the construction and arrangement without departing from the spirit or the invention and therefore the invention is not limited to what is shown in the drawing and described in the specification but only as indicated in the appended claims.

I claim:

-1. Intermittent absorption refrigerating apparatus comprising a hollow wall generator, a vessel within said generator spaced from the inner wall thereof and open at the bottom, heating means within said vessel, an analyzer coil above said generator and connected to the top of said vessel, a condenser above said analyzer coil and comprising a plurality of vertical tubes having a common header at each end and a casing enclosing a fluid tight chamber around said tubes, the lower header of said condenser being connected to said analyzer coil, an evaporator above said condenser and comprising a pair of concentric spaced shells the inner shell being open at the top and having a connection exterior of the outer shell from the bottom of the inner shell to the upper part of the space between the shells, a pipe connecting the upper header of saidcondenser to the space between the shells of said evaporator, a secondary condenser above the primary condenser, a fluid tight stand pipe extending from the level of the bottom oi the generator to the level of the top of the secondary condenser,

a fluid tight vessel in heat exchange relation with said analyzer coil, a pipe connecting the lower part of last said vessel to the lower end of said stand pipe, a pipe connecting the upper part of the space in the generator wall to the lowerend of said stand pipe, a pipe connecting the lower part of the space in the generator wall to the lower part of the chamber around the primary condenser tubes, a pipe connecting the upper part oi the latter to the lower part of said secondary condenser, and a pipe connecting the upper part of the latter to the upper end of said stand pipe.

2. In absorption refrigerating apparatus of the intermittent type, a hollow wall generator, a condenser above said generator, an evaporator above said condenser, a secondary condenser above said primary condenser, a fluid tight stand pipe extending from the level of the bottom of the generator to a level above the top of the primary condenser, pipes connecting in series, to form a closed fluid circuit, the hollow wall of the generator, the cooling chamber of the primary condenser, the secondary condenser, and the stand pipe, refrigerating fluid in said closed circuit, and means for controlling the liquid level in said stand pipe responsive to the difference in temperatures of the secondary refrigerant in the upper part of said circuit and the primary refrigerant in the system between said generator and evaporator.

3. in absorption refrigerating apparatus of the intermittent type, a hollow wall generator adapted to contain a solution oi refrigerant in an absorption liquid, an analyzer above said generator, a condenser above said analyzer, an evaporator above said condenser, a secondary condenser above said primary condenser, a fluid tight stand pipe extending from the level of the bottom of the generator to a level above the top of the primary condenser, pipes connecting in series, to form a closed fluid circuit, the hollow wall of the generator, the cooling chamber of the primary condenser, the secondary condenser, and the stand pipe, and a fluid tight vessel in heat exchange relation with said analyzer and connected to the lower end of said stand pipe.

4. In absorption refrigerating apparatus of the intermittent type, a generator-absorber, a cooling jacket around said generator-absorber, a condenser above said generator-absorber, a cooling jacket around said condenser, an evaporator connected to said condenser, a secondary condenser above said primary condenser, means for defining a vertically disposed fluid column including said secondary condenser and the cooling jacket around the primary condenser, means for defining a second vertically disposed fluid column, said fluid columns being in open communication at the top and connected at the bottom through the cooling jacket around the generator-absorber to form a closed fluid circuit, a volatile fluid in said closed circuit, and means for increasing the level of the liquefied fluid in said second column during the generating cycle and decreasing the level during the refrigerating cycle.

5. In absorption refrigerating apparatus of the intermittent type, a generator-absorber, a cooling jacket around said generator-absorber, a condenser above said generator-absorber, a cooling jacket around said condenser, an evaporator connected to said condenser, a secondary condenser above said primary condenser, means for defining a vertically disposed fluid column including said secondary condenser and the cooling jacket around the primary condenser, means for defining a second vertically disposed fluid column, said fluid columns being in open communication at the top and connected at the bottom through the cooling jacket around the generator-absorber to form a closed fluid circuit, a volatile fluid in said closed circuit, and means for increasing the amount of liquefied fluid in said second column to increase the level therein during the generating cycle and decrease the amount of liquid to lower the level during the refrigerating cycle.

6. In absorption refrigerating apparatus of the intermittent type, a generator-absorber, a cooling jacket around said generator-absorber, a condenser above said generator-absorber, a cooling jacket around said condenser, an evaporator connected to said condenser, a secondary condenser above said primary condenser, means for defining a vertically disposed fluid column including said secondary condenser and the cooling jacket around the primary condenser, means for defining a second vertically disposed fluid column, said fluid columns being in open communication at the top and connected at the bottom through the cooling jacket around the generator-absorber to form a closed fluid circuit, a volatile fluid in said'closed circuit, a fluid tight container communicating with said second column, and means for heating said container during the generating cycle and cooling said container during the refrigerating cycle.

7. In combination with intermittent absorption refrigerating apparatus, a jacket around the generator-absorber, a jacket around the condenser, a secondary condenser above the primary condenser, means deflning a vertically disposed fluid column including said secondary condenser and said jacket around the primary condenser, means defining a second vertically disposed fluid column, said fluid columns being in open communication at the top and connected at the bottom through said jacket around the generator-absorber to with said second column and associated with the refrigerating apparatus in such relation that it is heated during the generating cycle and cooled during the refrigerating cycle.

8. In combination with absorption refrigerating apparatus of the intermittent type having a cooling jacket around the generator-absorber and a cooling jacket around the condenser, means defining a closed cooling fluid circuit including two vertically disposed fluid columns, one of said columns including the cooling jacket around the condenser, means for cooling the upper part of said closed circuit, said cooling jacket around the generator-absorber being included in the lower part of said closed circuit between the said columns, a volatile fluid in said closed circuit, and means for increasing the Weight of the fluid in the other of said columns during the generating cycle and decreasing the weight during the refrigerating cycle.

9. In combination with absorption refrigerating apparatus of the intermittent type having a cooling jacket around the generator-absorber and a cooling jacket around the condenser, means defining a closed cooling fluid circuit including two vertically disposed fluid columns, one of said columns including the cooling jacket around the condenser, means for cooling the upper part of said closed circuit, said cooling jacket around the generator-absorber being included in the lower part of said closed circuit between the said columns, a volatile fluid in said closed circuit, and means for supplyingliquefled fluid tov the other of said columns to increase the level therein during the generating cycle and withdrawing liquefied fluid to lower the level during the refrigerating cycle.

10. In combination with refrigerating apparatus of the intermittent absorption type, a secondary evaporating-condensing cooling system adapted to alternately cool the condenser during the generating cycle and the generator-absorber during the refrigerating cycle.

11. In refrigerating apparatus of the intermittent absorption type, means for circulating cooling fluid alternately in heat exchange relation with the condenser during the generating cycle and with the generator-absorber during the refrigerating cycle responsive to the input.

12. In combination, refrigerating apparatus of the intermittent absorption type including a rectifier between the generator-absorber and the condenser and a secondary evaporating-condensing cooling circuit adapted to cool the primary condenser responsive to the difference in temperatures of the secondary condenser and said rectifier.

13. In the art of refrigerating with intermittent absorption type apparatus, cooling the condenser during the generating cycle and the generator-absorber during the refrigerating cycle by maintaining volatile liquid in heat exchange relation with the generator-absorber, balancing two columns of volatile liquid communicating at their lower ends through the said liquid in heat exchange relation with the generator-absorber. supplying volatile liquid to one of said columns to increase its height for the duration of the generating cycle, absorbing heat from the generator-absorber to vaporize the volatile liquid in heat exchange reation therewith to create a vapor pressure under the other of said columns to raise the latter to the level of the condenser to balance the first said liquid column, absorbing heat from the condenser to vaporize liquid in said second column, condensing the vapor and returning the liquid to said second column, removing volatile liquid from first said column to decrease the height thereof for the duration of the refrigerating cycle, condensing vapor created by heat fromthe generator during the generating cycle to lower the height of said second column, transferring heat of absorption during the refrigerating cycle tovaporize the volatile liquid in heat exchange relation with the generatorabsorber, condensing the vapor and returning the liquid to be revaporlzed.

14. In the art of refrigerating with intermittent absorption type apparatus, cooling the condenser during the generating cycle by balancfng two columns of volatile liquid, supplying volatile liquid to one of said columns to raise the height thereof for the duration of the generating cycle, maintaining a quantity of volatile liquid in heat exchange relation with the generator, absorbing generator input heat to vaporize the last said quantity of volatile liquid to create vapor pressure under the second of said columns to raise the height thereof to balance the first said column, absorbing heat from the condenser to vaporize volatile liquid in said second column, condensing the vapor and returning the liquid to said second column.

15. In the art of refrigerating with intermittent absorption apparatus, supplying volatile liquid to cool the condenser by vaporization during the generating cycle, transferring the liquid to cool the generator-absorber by vaporization during the refrigerating cycle, condensing the vaporized fluid, and returning the liquid to the part being cooled.

16. In the art of refrigerating with intermittent absorption apparatus, cooling the condenser during the generating cycle and the generator-absorber during the refrigerating cycle by absorbing heat from the part to be cooled to vaporize a volatile liqu'd, condensing to a liquid the vapor formed during both cycles by the same means, and returning the liquid to be again vaporized by heat from the part being cooled.

17. In the art of refrigerating with intermittent absorption apparatus, supplying a quantity of volat'le liquid to alternately cool the condenser during the generating cycle and the generatorabsorber during the refrigerating cycle.

18. The method of cooling alternately at different levels which comprises maintaining aquantity of volatile liquid at one level, balancing two columns of volatile liquid which are in communication at their lower ends through said quantity of liquid, maintaining a control quantity of volatile fluid in communication with one of said columns, heating said control fluid to exert a ressure for forcing liquid into said column to increase the weight thereof, heating first sad quantity of liquid to exert a pressure under the other of said columns to raise the liquid level thereof to balance the first said column, removing heat at the new level to vaporize liquid in the second column, condensing the vapor, returning l'quid to the second column, cooling said control fluid to reduce the pressure thus removing liquid from first said column to decrease the weight thereof, removing pressure under the second column to again balance the first column, removing heat at the first said level to vaporize first said quantity of volatile liquid, condensing the vapor and 'returning the liquid through said second column.

19. The method of cooling which comprises balancing two columns of volatile liquid, maintaining a control quantity of volatile fluid in communication with one of said columns, heating and cooling said control fluid to increase and decrease the weight of said column, applying and removing pressure below the other of said columns to balance the first said column, absorbing heat to vaporize liquid in the second column,condensing the vapor, and returning the liquid to the second column.

20. The method of cooling at a plurality of levels which comprises balancing two columns of volatile liquid, supplying volatile liquid to vary the weight of one of said colunms, generating vapor below the other of said columns to raise the level thereof to balance the first said column, absorbing heat to vaporize liquid in the second said column, condensing the vapor, and returning the liquid to said second column.

21. The method of cooling at a plurality of levels which comprisescontrolling the height of a variable column of volatile liquid, balancing said column with a second column of volatile liquid, absorbing heat to vaporize liquid in said second column, condensing the vapor, and returning the liquid to said second column.

22. A liquid seal valve comprising a liquid trap for maintaining a liquid column, a closed vessel for containing a volatile fluid communicating with said column below the liquid level, and means for heating and cooling said vessel.

23. A liquid seal valve comprising a liquid trap for maintaining a liquid column, and means for controlling the weight of liquid in said column.

24. In a fluid circulating system means for controlling circulation comprising a liquid trap for maintaining a liquid column in said system, and means for varying the amount of liquid in said column.

25. In a fluid circulating system means for controlling circulation comprising a liquid trap for maintaining a liquid column, a closed vessel for containing a volatile liquid in communication with said column, and means for heating and cooling said vessel.

26. The method of controlling fluid circulation which comprises maintaining a liquid column in the fluid path and controlling the height of said liquid column by the addition and removal of liquid.-

2'7. The method of controlling fluid circulation which comprises maintaining a liquid column in the fluid path, maintaining a confined quantity of volatile liquid in communication with said column below the liquid level, heating said quantity of liquid to increase the height of said column and cooling of the resulting vapor to decrease the height of said column.

28. The method of controlling fluid circulation which comprises maintaining a liquid seal in the fluid path, maintaining a confined quantity of volatile liquid in communication with said seal and heating said quantity of liquid to control the amount of liquid in said seal.

29. In absorption refrigerating apparatus of the intermittent type, a secondary evaporatingcondensing system for alternately cooling the condenser and absorber comprising a condenser cooling element, an absorber cooling element, a secondary condenser above said elements, the secondary condenser and said elements being orbitally connected to form a closed fluid system, and a liquid trap in the system on each side of said absorber cooling element to maintain liquid columns for balancing the vapor pressure therein during the generating cycle.

30. In absorption refrigerating apparatus of the the intermittent type, a secondary evaporatingcondensing system for alternately cooling the condenser and absorber comprising a condenser cooling element, an absorber cooling element, a secondary condenser above said elements, the secondary condenser and said elements being orbitally connected to form a closed fluid system, a liquid trap in the system on each side of said absorber cooling element to maintain liquid columns for balancing the vapor pressure therein during the generating cycle, and means for decreasing the amount of liquid in the column between the absorber cooling element and the secondary condenser during the refrigerating cycle to allow vapor to pass from the former to the latter.

DONALD B. KNIGHT. 

